Deflection compensation system for press

ABSTRACT

A system for providing for compensation for deflection during a compacting press operation. The system is operable in conjunction with a separate inner and outer ram arrangement so that immediately after press operation and throughout the press eject operation there is provided a preloading of the inner ram upwardly in supporting relationship to the part. A predetermined space is provided between the inner and outer rams. The particular space adjustment means provided for deflection compensation also permits adjustment where it is necessary to provide overfill or underfill where these conditions are required.

D United States Patent 1 1111 3,733,154 Smith et al. 1 May 15, 1973 54]DEFLECTION COMPENSATION 3,172,156 3/1965 3616611 ..425/78 SYSTEM FORPRESS 3,191,232 6 1965 Haller..... ....425/78 3,337,916 8/1967Smith..... 425/351 [75] IIlVCl'ltOl'SI Joseph E. Smllh, B1rm1ngham; 3 44 9 9/19 9 Smithum 42 7 Georges DeTroyer, Grosse 3,524,220 8/1970Davison ..425/78 Raymond P. DeSantis, Royal Oak, 3,561,056 2/1971 Smithetal..... 425/168X all of Mich. 3,611,498 10/1971 Hedin ..425/4143,647,332 3/1972 Schmaus... ..425/78 [73] Assigneez Wolverme-Pentromx,Inc., Lincoln 3,664,784 5/1972 Sibley 425/351 X Park, c 3,669,582 6/1972Smith ..425/7s 3,671,164 6 1972 El Hara 6131. .425 414 [22] 19713,671,157 6/1972 Smith ..425/78 21 A 1. No.2 172,510 1 pp PrimaryExaminer-J. Howard Flint, Jr. 52 U.S.Cl. ..425/78,425/345,425/406,Haukeeta" 425/414 57 ABSTRACT [51] Int. Cl. ..Bb 11/04 j 5s 1 Field 61Search ..425/78, 168, 12s, A System f vrovldm'g for compensatwn fordeflec- 425/351, 414, 214, 141, 149, 344, 415, tion durmg a compactmgpress operation. The system is operable in conjunction with a separateinner and [56] References Cited outer ram arrangement so thatimmediately after press operation and throughout the press ejectoperation UNITED STATES PATENTS there is provided a preloading of theinner ram upwardly in supporting relationship to the part. Apredetermined space is provided between the inner 2:82l:748 2/1958 andouter rams. The particular space adjustment 2,932,063 4/1960 meansprovided for deflection compensation also per- 3,149,373 9/1964 mitsadjustment where it is necessary to provide over- 3,154,812 11/1964 fillor underfill where these conditions are required. 3,168,759 2/1965 5Claims, 5 Drawing Figures alr exhaust PAIENTEB HAYI 5l973 733 154 SHEET1 [IF 4 34 oirin Joseph E.Smith 52 Georges D. DeTroyer am" Raymond P.DeSomis must INVENTORS F/g BY PATENTED MAY] 5l973 SHEET 3 BF 4 i 52 Il46 uirexhaust curln Fig-3 air in Joseph E. Smith Georges D. DetroyerRaymond P DeSomis INVENTORS f iw w PATENTED 3,733,154

' SHEET u [If 4 J G (M //9w I I 20w 7 N zz Fig-4 eject die plate level Hup f'll d p ff fi d romzz movement J 0 a r mp down o'rotoflon presselect fill inner romza movement A. for deflection L compensation do ymB. for overfill down C. for underfill up down I I I 5 Joseph E.Srni1hGeorges D. DeTroyer Raymond F. DeSontis INVENTCRS BY Attorneys-BACKGROUND OF THE INVENTION In precision press operation, particularlywhere the parts are relatively thin and fragile and are subject to tighttolerances such as for example integrated circuit substances, it isnecessary to provide some arrangement to relieve the initial press forceby which the compacting is accomplished. Various types of ramconstruction to relieve the press force have been provided, whichinclude complex resilient tool punch constructions and cushioning airarrangements. Reference is made to US. Pat. No. 3,561,056 issued toJoseph E. Smith et al. for Tool Set for Powder Compacting Press for ashowing of a press adaptable for us with the present invention. Thatpatent is of common ownership with the present application.

BRIEF SUMMARY OF THE INVENTION The present invention provides adeflection compensation system employing a particular adjustable spacingdevice coupled between the separate inner and outer press rams. Ashereinbefore mentioned, after the powdered material has been compacted,the initial withdrawal of the punch force from the underside of the partmay cause thin or fragile parts to be damaged by the suction effectcreated by the downward movement of the punch away from the part. Inaddition, the force of compacting during the press operation istypically transmitted through a cam mounted on a cam shaft and connectedto one end of a lever-like treadle. During the press compacting stroke,a considerable load is exerted on the several internal elements of themachine. This causes these elements to deflect elastically aconsiderable amount. As soon as the punch is withdrawn from the part,these members return to their original state leaving a space between thepart and the punch. This can cause damage to the part. The systemaccording to the present invention allows the punch tool to remain insupporting contact with the compacted part after pressing withoutexerting any substantial force, while permitting relief of the greaterpart of the compacting pressure exerted on the part during thecompacting process. In addition, the several movements of the press ramsare controlled through a pneumatic cylinder arrangement which isparticularly adapted for the double ram control and for the operation ofthe deflection compensation system according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention, together withits advantages and features, will be best understood by reference to theaccompanying specification and to the several drawings in which likeparts are referred to by like numerals, and wherein:

FIG. 1 is a longitudinal cross-sectional view of a press showing thevarious press parts in their fill operation position, with parts brokenaway to simplify the showing of the embodiment;

FIG. 2 is a view substantially similar to FIG. 1 in which the press andrams are illustrated in their press position;

FIG. 3 is a view substantially similar to those of FIGS. 1 and 2 butillustrating the eject position of the press and rams;

FIG. 4 is a cross-sectional view showing a somewhat modified embodimentof the present invention in which a modification of the parts is made tocontrol core rod operation; and

FIG. 5 is a diagram illustrating the timing of the relative movements ofthe inner and outer rams during a full cycle of press operation.

DETAILED DESCRIPTION FIG. 1 shows the basic ram and press parts whichare ordinarill employed in a precision press for compacting powderedmaterials for use in computer memory cores, beads, pellets, porousbushings and the like. In the initial fill position, as it is shown inFIG. 1, a powdered material feed shoe 10 is placed over a die cavity 11provided in a die bushing 14, which in turn is held in the die plate 16.The punch tool 18 is shown as it is positioned in the lower end of thedie bushing 14 during the fill operation of the press. The pressoperating mechanism is shown below the punch tool 18 and incudes as itsmajor parts a pair of separate rams, namely, an inner ram 20 and an,outer ram 22. The inner ram 20 has formed near its upper end an annularextension 24, which iscoupled through a series of intermediate elementsto punch stem 26. The outer ram 22 has an annular extension at its upperend, denoted by the numeral 28. During the fill operation as illustratedin FIG. 1, the upper surface of the extension 28 of the outer ram 22will be seen to be in engagement with the lower surface of the punchstem 26. A threaded nut 30 is mounted on a matching thread portion 32formed on the outside diameter of the lower end of the punch stem 26.The threaded nut 30 further includes at its lower end a lip 34, which isadapted to retain the outer ram 22 in its drop-off position, as will beshown in FIG. 3 hereinafter. The nut 30 is adjustable by turning to varythe distance A to provide exactly the degree of compensation requiredfor deflection during the subsequent press operations, as will be shownin FIGS. 2 and 3 hereinafter.

The biasing system for the inner ram 20 and outer ram 22 is shown at thebottom of the FIG. 1 drawing. The drive system is a pneumatic system,including an outer cylinder 36 and an inner air cylinder 38. It will beseen that the respective air cylinders serve to drive the inner ram 20and the outer ram 22, one independently of the other or in unisondepending upon the particular cycle of operation being carried out. Itwill be noted that the lower end of the outer ram 22 terminates in acylindrical, annular extension 40, having around its outer edge a seal42 engageable with the inner walls of the cylinder 36. There is formedcentrally through the outer ram 22 a longitudinal, cylindrical opening23, which telescopically retains the lower part of the inner ram 20 forreciprocal movement therein. The inner ram 20, terminating at its lowerend in a cylindrical, annular extension 44, likewise has an outer seal46 in slidable engagement with the inner surface of the inner aircylinder 38.

In the fill operation illustrated in FIG. 1, the air flow is, asindicated by arrows, inwardly through a pair of ports 48 and 50, formedin cylinders 36 and 38, respectively, with exhaust provided through alower port 52 positioned at the bottom of the cylinder 38. Accordingly,there is a downward biasing force provided against both the inner ram 20and the outer ram 22 to permit the filling of the die plate 16 openingwith the powdered material for the part.

FIG. 2 illustrates the parts in their position for a compacting pressoperation. At the upper end of the drawing, an anvil 54 has replaced theouter feed shoe 10. The anvil 54 is positioned in abutment with theupper surface of the die plate 16. Both the inner ram 20 and the outerram 22 are provided with a downward, biasing force through the operationof the respective air cylinders 36 and 38 after the manner shown inFIG. 1. In the press operation position, through a suitable camoperating mechanism not shown, the entire rarn system including the rams20, 22 and their associated parts are driven upwardly to apply a forceto compact the part 56. Reference may be made to the aforementioned US.Pat. No. 3,561,056 for an example of a cam operating mechanism suitablefor ram operation. It will be noted that during the press operation, asshown in FIG. 2, the projection 28 at the upper end of the outer ram 22continues in engagement with the lower surface of the punch stem 26 asboth rams are moved upwardly together in a press stroke.

FIG. 3 illustrates the position of the parts in the eject operation ofthe press. The pneumatic drive system, as illustrated in FIGS. 1 and 2,has been changed and through a suitable valve control system thedirection of air is as shown, with a continuous flow in at the ports 48and 52 and at the same time air exhaust from the port 50. In this mannerimmediately following the press operation, it will be seen that theinner ram 20 is provided with a continuing upward force to bias thepunch 18 upwardly against the part 56, while simultaneously the pressforce is relieved by a downward movement of the outer ram 22. Inaddition, following the press operation and throughout the eject cycle,as illustrated in FIG. 3, there is a drop-off of the outer ram 22 sothat at its upper end the upper surface of extension 28 is out ofcontact with the lower end of the punch stem 26. Spacing ispredetermined by threaded nut 30 which provides a clearance preset withthe spacing A.

The eject operation includes positioning of a vacuum pickup head 58adjacent to the upper end of the part 56 so that the part can be removedfrom the upper end of the die bushing. At the conclusion of the ejectoperation, the air flow path is restored to the same state as wasillustrated in FIGS. 1 and 2, with air flow in at the ports 48 and 50and air flow out at the port 52. Both the inner ram 20 and the outer ram22 are again subjected to a downward biasing force in preparation for arepetition of the press sequence, beginning with the fill operation asit was illustrated in FIG. 1.

FIG. 4 shows an alternate embodiment of the invention which provides acore rod 19 for providing a central opening in the part 56. The partsare modified in the manner shown so that the core rod 19 is centrallyjournalled in a longitudinal opening 21 fomied in the punch 18. The cordrod 19 is connected to the upper end of the inner ram 20. The connectionincludes a lower flange 19a, which is retained within a cylindricalopening 20a at the enlarged upper end of the inner ram 20. Thisconnection permits the core rod 19 to move upwardly and downwardlyindependently of the movement of the tool punch 18. This provides adistinct advantage where the parts formed are relatively long anddensely compacted. It is possible to reduce the eject force, as well ascore rod wear, by allowing the core rod 19 to be pulled up with the partduring the eject operation until the expansion of the part 56 once outof the die cavity permits it to become freed from the core rod 19. Thecore rod 19 is then retracted in the usual mode of operation downwardlywith the inner ram 20.

DESCRIPTION OF OPERATION The description of operation will now be madewith respect to the movements of the main operating elements, namely theinner ram 20 and the outer ram 22. Reference is made to the timingdiagram of FIG. 5 which substantially assists in clarifying the relativemovement of the parts during the several different stages of operation.With respect to deflection compensation, it will be seen that at thebeginning of the fill operation, both the inner ram 20 and the outer ram22 are preloaded downwardly. This keeps the punch stem 26 lower surfaceagainst the upper end of the outer ram, as illustrated in FIG. 1. Thiscondition is also illustrated in FIG. 2 and it continues throughout theentire fill operation and until just after the press operation iscompleted. Immediately following the press operation and throughout theeject operation, thP inner ram 20 is preloaded upwardly so that thespace A exists between the bottom end of the punch stem 26 and thP upperend of the outer ram 22. This condition is best shown in the FIG. 3drawing. It will be appreciated that the adjustment for the amount ofdeflection compensation may be readily accomplished by starting pressoperation with the threaded nut 30 up tight so that the space A does notinitially exist. As press try-out is made, the nut 30 is graduallyturned to increase the space A" until the parts being produced cease toshow any indication of buckling. At this point, the deflectioncompensation setting is sufiicient fo the parts being made and the nut30 can be locked in this position.

As has already been indicated, the deflection compensation system andthe adjusting nut 30, together with the pneumatic ram drive arrangementdisclosed, facilitate providing for overfill in the operation of thepress. To provide for overfill, both the outer ram 22 and the inner ram20 are preloaded downwardly in the usual manner with the punch stem 26maintained in abutment against the upper surface of the outer ram 22.The timing is difierent since relatively early in the fill position ofthe rams there is a drop-off of the inner ram 20. The overfill operationis clarified in the timing diagram of FIG. 5, with respect to the up anddown movement of the inner ram 20. The overfill arrangement pushes someof the powder material 12 back out of the filled cavity, into the powderfeed shoe 10, before it moves away at the conclusion of the filloperation. The amount of overfill may be adjusted by selective rotationof the threaded nut 30.

For underfill operations, the inner ram 20 is preloaded upwardly fromthe start of the fill operation until the powder feed shoe 10 moves awayfrom the die cavity. This timing is shown by the diagram of FIG. 5. Justbefore the press operation is initiated the inner ram 20 is preloadeddownwardly so that the load of powder material 12 in the cavity movesdownwardly, thus creating an air space above it in the die bushing 14.This particular mode of operation can be quite important when upperpunches are used to allow the upper punch to enter the cavity withoutprecompacting the powder from the top. Here again, the amount ofunderfill is readily preset by adjustment of the threaded nut 30.

It will thus be seen that there has been provided an improved deflectioncompensation system for a compacting press, which system provides forready adjustment for overfill and underfill in the manner desired. In alike manner, the deflection compensation system and ram arrangement canbe simply altered to provide for core rod movement when it is requiredfor production of an apertured part.

What is claimed is:

l. A deflection compensation system for a press for compacting powdermaterials by a tool through successive fill, press and eject operations,said deflection compensation system comprising a pair of concentric ramsdefining an inner ram rigidly connected to a support member for the tooland an outer ram operable independently of said inner ram and having anend engageable with an end of the tool support member means for biasingboth rams downwardly during said fill operation; means for driving saidouter ram during said press operation with the end of said outer ram indriving engagement with the end of said tool support member; saidbiasing means operative to continue the upward biasing of the inner ramand tool support member subsequent to retraction of the outer ram andduring said eject operation; and adjustable spacing means disposedproximate the adjacent ends of said tool support member and said outerram, said spacing member means comprising a sleeve member adjustablythreaded on the end of the said tool support member, said sleeve membercomprising an abutment engageable with said outer ram for maintainingthe end of said tool support member and the end of said outer ram inrelative longitudinal spaced relationship.

2. The combination as set forth in claim 1 wherein separate fluidbiasing means are operatively connected to said inner and outer rams.

3. A deflection compensation system for a cyclically operated presscomprising an inner ram and an outer ram telescopically disposed onewithin the other; a press tool holder and a press tool mounted on an endof said inner ram; an operating means for providing reciprocation ofsaid outer ram toward and away from a part; first abutment means forrigidly coupling said outer and inner rams during reciprocation of saidouter ram in a direction toward said part during a work cycle of saidpress; second abutment means for rigidly coupling said outer and innerrams during reciprocation of said outer ram away from said part; andcontrollable biasing means for controllably reciprocating one ramrelative to the other within the limits provided by said first andsecond abutment means.

4. The deflection compensation system of claim 3 wherein said first andsecond abutment means are adjustable one relative to the other.

5. The deflection compensation system of claim 3 wherein saidcontrollable biasing means comprises a cylinder mounted on one of saidrams, a double acting piston mounted on the other of said ramsreciprocable in said cylinder, and means for introducing fluid in saidcylinder for reciprocating said piston.

1. A deflection compensation system for a press for compacting powder materials by a tool through successive fill, press and Eject operations, said deflection compensation system comprising a pair of concentric rams defining an inner ram rigidly connected to a support member for the tool and an outer ram operable independently of said inner ram and having an end engageable with an end of the tool support member means for biasing both rams downwardly during said fill operation; means for driving said outer ram during said press operation with the end of said outer ram in driving engagement with the end of said tool support member; said biasing means operative to continue the upward biasing of the inner ram and tool support member subsequent to retraction of the outer ram and during said eject operation; and adjustable spacing means disposed proximate the adjacent ends of said tool support member and said outer ram, said spacing member means comprising a sleeve member adjustably threaded on the end of the said tool support member, said sleeve member comprising an abutment engageable with said outer ram for maintaining the end of said tool support member and the end of said outer ram in relative longitudinal spaced relationship.
 2. The combination as set forth in claim 1 wherein separate fluid biasing means are operatively connected to said inner and outer rams.
 3. A deflection compensation system for a cyclically operated press comprising an inner ram and an outer ram telescopically disposed one within the other; a press tool holder and a press tool mounted on an end of said inner ram; an operating means for providing reciprocation of said outer ram toward and away from a part; first abutment means for rigidly coupling said outer and inner rams during reciprocation of said outer ram in a direction toward said part during a work cycle of said press; second abutment means for rigidly coupling said outer and inner rams during reciprocation of said outer ram away from said part; and controllable biasing means for controllably reciprocating one ram relative to the other within the limits provided by said first and second abutment means.
 4. The deflection compensation system of claim 3 wherein said first and second abutment means are adjustable one relative to the other.
 5. The deflection compensation system of claim 3 wherein said controllable biasing means comprises a cylinder mounted on one of said rams, a double acting piston mounted on the other of said rams reciprocable in said cylinder, and means for introducing fluid in said cylinder for reciprocating said piston. 